In many medical procedures, various physiological conditions present within a body cavity need to be monitored. These physiological conditions are typically physical in nature—such as pressure, temperature, rate-of-fluid flow, and provide the physician or medical technician with critical information as to the status of a patient's condition.
One device that is widely used to monitor conditions is the blood pressure sensor. The sensor is typically included in a guide wire for intravascular measurements. A blood pressure sensor senses the magnitude of a patient's blood pressure, and converts it into a representative electrical signal that is transmitted to the exterior of the patient. For most applications it is also required that the sensor is electrically energized.
Some means of signal and energy transmission is thus required, and most commonly extremely thin electrical cables are provided inside the guide wire, which itself is provided in the form of a tube (in the order of 0.35 mm in outer diameter), oftentimes made of stainless steel. In order to increase the bending strength of the tubular guide wire, a core wire is positioned inside the tube. The mentioned electrical cables are positioned in the space between the inner lumen wall and the core wire.
A large flexibility of the sensor guide is advantageous in that it allows the sensor guide to be introduced into small and tortuous vessels. It should, however, also be recognized that if the core wire is too flexible, it would be difficult to push the sensor guide forward into the vessels, i.e. the sensor guide must possess a certain “pushability”. Furthermore, the sensor guide must be able to withstand the mechanical stress exerted on the core wire especially in sharp vessel bends.
EP patent 1 475 036, assigned to the same assignee as in the present application, shows a sensor wire assembly, where electrical micro-cables extend along a core wire and along the length of a guide wire. One drawback with this design is that the guide wire when rotated has a tendency to store the elastic energy or the built up torque and release it, resulting in a rotational whipping.
The object of the present invention is to achieve an improved sensor guide wire that has a more predictable movement pattern compared to prior art sensor guide wires.